1. Field of the Invention
The present invention relates to an image data processing apparatus which performs spatial filtering of image data so as to extract and display image data effective for diagnosis by a physician in a medical image diagnosis apparatus.
2. Description of the Prior Art
Digital signal processing techniques are more frequently being used in medical image processing by medical image processing apparatuses such as X-ray CT apparatuses or digital radiography apparatuses. In particular, spatial filtering has an important role as a technique for performing smoothening, or edge enhancement.
However, at present, spatial filtering is utilized for slight edge enhancement with fixed frequency characteristics for filtering. Although such spatial filtering is effective for diagnosis, data effective for diagnosis which are provided together with unnecessary data, cannot be effectively utilized. A digital radiography apparatus for obtaining an X-ray transmission image in the form of digital data has a density resolution of 200 to 500 tone or gradation (gray) levels. In contrast to this, a display device, e.g., a CRT has only about 30 gradation levels. Moreover a viewer has the ability to distinguish about 10 to 20 gradation levels. For this reason, there have been many types of image data which are included in the original image data and which are effective for diagnosis and yet which cannot be used for reproducing fine contrast.